1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material containing therein a coupler which forms a heterocyclic azo dye by a coupling reaction of the coupler and an oxidized developing agent. Further, the present invention relates to a method of preparing a heterocyclic azo dye which can be prepared by this coupling reaction, and to a heterocyclic compound which provides the dye.
2. Description of the Related Art
In a silver halide photographic light-sensitive material (referred to as a "light-sensitive material" in some cases, hereinafter) using a subtractive color process, a color image is formed by dyes of the three primary colors, i.e., yellow, magenta, and cyan. In color photography using an existing p-phenylenediamine-based color-developing agent, a .beta.-acylacetanilide-based compound is used as the yellow coupler. However, hues of the yellow dye obtained from these couplers become reddish, thus making it difficult to obtain yellow hues of high purity. Further, there have been problems in that, since the molar extinction coefficient of the dye is small, a large amount of coupler or silver halide must be used in order to obtain a desired density of the formed color and the film thickness of the light-sensitive material thus becomes larger, and sharpness of the obtained color image thereby deteriorates. Moreover, since this dye has a tendency to decompose under high temperature and/or high humidity, there are problems in image storage stability after the light-sensitive material has been subjected to developing processing. Accordingly, it is desired to improve problems such as those described above.
In order to solve these problems, improvement of an acyl group and an anlide group has been performed. Recently, the 1-alkylcyclopropylcarbonylacetanilide-based compound disclosed in Japanese Patent Application Laid-Open (JP-A) No. 4-218042, the malon di(cyclic amide) coupler disclosed in Japanese Patent Application Laid-Open (JP-A) No. 5-11416, and the like have been proposed as a coupler obtained by improving a conventional acylacetanilide and derivatives thereof. A dye produced from such a coupler has been improved in respect of hues and molar extinction coefficients over conventional dyes. However, the dye is not improved satisfactorily in respect to image storage stability. In addition, since the structure of the coupler has become complicated, the manufacturing cost of the coupler has become expensive thus causing a problem in that such a coupler is less practical.
Instead of a conventional coupler which produces an azomethine dye, the indazole-based compound disclosed in Great Britain Patent No. 875470 has been proposed as a yellow coupler which forms an azo dye having a high extinction coefficient However, since the dye produced by the coupler has an essential problem in that an intramolecular hydrogen bond occurs under neutral condition and the absorption peak or band thereby shifts to higher wavelength, the dye cannot be used practically. Further, as a yellow coupler which forms an azo dye having a high extinction coefficient, there has been proposed the compounds disclosed in JP-A No. 10-148921. However, there is the problem that the pKa of this coupler is so high that the coupling activity of this coupler is insufficient, and when the pKa is lowered in order to improve the coupling activity, the hues deteriorate. As a result, this coupler cannot be used practically.
Further, there has been a strong demand for using azo dyes, whose molecular extinction coefficient is high and which have excellent hues and storage stability, not only for silver halide photographic light-sensitive materials, but also as a general dye, as well as a dye for images including dyes used in inks for ink jet printers. The development of a simple method of preparing an azo dye and in particular, a method of preparing an azo dye using a coupler have been desired.